File Juicer is a small Mac OS X application that extracts images, movies, text, and other useful data from practically anything. It's useful to Aperture users in two important ways: it can recover usable images from the library if the masters are lost and and can scrounge deleted images from memory cards.

One of the hazards of working with referenced image masters is that their management is the responsibility of the owner. Accidental deletions are not that uncommon, and if that happens then while Aperture can display the images, it cannot export or otherwise use any of the versions that are based on the lost masters. If the masters are truly lost -- no back ups, nothing in the trash -- then whatever images can be found become valuable.

If high resolution previews were generated, then these can be extracted from the Aperture library by simply selecting the thumbnail images in the browser and dragging them to the desktop. They will be in JPEG format and at a size and resolution that depends on the settings in Aperture's preferences:

If there are no previews, then attention turns to the thumbnail files that Aperture stores in each project. It is these images that are used to display the on-screen thumbnails in the browser pane and as placeholder images in the viewer while Aperture processes the RAW image. The files that contain the thumbnails are called AP.Tinies, AP.Minis, and AP.Thumbnails and contain images at 32, 256, and 1024 pixel sizes respectively. They are also present in exported projects, but not in vaults.

To get to the thumbnails, I control-click on the library and select Show Package Contents. Then I navigate down to the project of interest and open that with a control-click and Show Package Contents:

The AP.Thumbnails file is one big chunk of binary data, but inside there are complete JPEG images. File Juicer will go into it and locate and extract the JPEGs without knowing the format of the file.

I launch File Juicer and check that the preferences are set to include JPEG images (at least):

I also make sure that the extracted files will be stored somewhere sensible, such as on the desktop, because I don't want the extracted images put inside my Aperture library:

With the selections I have made, File Juicer will put each image type into a separate folder and create a parent folder for those. It will also get an HTML index file for easy browsing. To start scanning for images, I drop the AP.Thumbnails file from my project onto the main File Juicer window and wait for it to process:

After processing I get a new folder on my desktop containing the images:

And I can either open the jpg folder and browse the image icons in the Finder (or watch a slide show), or click on the index.html icon and see all the images in a browser window as a panoramic display:

Now my images have been extracted, I can reimport them into Aperture and sort through them. They will be smaller then the originals -- only up to 1024 pixels on a side-- and there will be one image per version. So a single lost master will result in five recovered JPEGs if it had five versions in that project. This is good because I get my adjusted images, albeit at low resolution.

Since File Juicer is scavenging for JPEGs rather than following any information that Aperture provides, there are some side-effects. The first is that there may be old images or possibly corrupted images in the folder of JPEGs. The second is that the names of the images are sequential and bear no relationship to the order in which they were taken or anything else. The third is that there is no EXIF or other metadata in the JPEGs, so all the keywords, camera and shooting data are lost.

File Juicer will also recover RAW and other images that have been deleted from camera cards, so if masters have been lost it is possible that they can be obtained that way. The process is very similar to the thumbnail recovery described here, except that there is an extra step at the beginning where File Juicer creates a disk image of the card and scans that.

The File Juicer web site has a page dedicated to its use with Aperture, and one about RAW image formats.